This invention relates to apparatus for the inspection of pallets and for aligning a stack of pallets in a substantially continuous operation.
Ouellette Pat. No. 4,557,656 illustrates and describes apparatus for handling pallets, operable either in a palletizing or depalletizing mode and its subject matter is incorporated herein by reference. The present invention, like the aforementioned Pat. No. 4,557,656, incorporates a system of elevators for delivering pallets to and from the upper area of a frame where the pallets can be transferred and handled for either or both the functions of pallet inspection and alignment of a stack of pallets.
In the present invention, the apparatus incorporates a frame having an infeed bay, an inspection bay, and an outfeed bay located adjacent one another. Each bay has an independent elevator. Thus, the infeed bay receives a stack of pallets from a conveyor and an elevator raises the pallets within the infeed bay. The elevator is indexed upwardly as pallets are removed from the top of the stack.
At the top of the infeed bay, there are transversely movable plates for engaging the side edges of an uppermost pallet on the stack. These plates are biased inwardly by a pneumatic or hydraulic piston and cylinder assembly connected between the plates. If the uppermost pallet is askew relative to the plates, the pressure applied by the plates initially pivots that uppermost pallet into alignment with the plates after which the plates firmly grip the pallet. Because the piston and cylinder assembly floats with the positions of the plates, the plates will not center the pallet relative to the frame at this time. Rather, the elevator will lower the pallet stack to create a small gap (about 1/2 inch) between the top of the stack and the pallet gripped between the plates. Thereafter, with interference between the gripped pallet and the stack eliminated, another piston and cylinder assembly having chains connected to both plates aligns the gripped pallet with the longitudinal center of the frame. A transversely movable pallet car assembly at the upper end of the frame then receives the aligned pallet, upon release by the plates, and a pusher plate properly locates the longitudinal position of the pallet on the pallet car assembly. Thereafter, the pallet car assembly transfers the pallet from the top of the infeed bay to the top of the inspection bay.
At the inspection bay, there are gripper arms that grip the pallet at its side edges and rotate the pallet through increments of 180.degree. each. The top of the pallet can first be visually inspected and then, upon the first 180.degree. increment of rotation, the bottom of the pallet can be inspected. The elevator in the inspection bay is for receiving a rejected pallet. If the operator determines that a pallet should be rejected, he initiates operation of the reject cycle, such as by depressing a button, so that the grippers will separate and drop the pallet onto the inspection bay elevator. The rejected pallets are stacked on the inspection bay elevator and the elevator is indexed downwardly as pallets are stacked on it. These rejected pallets are transferred to a conveyor that removes them from the apparatus.
If a pallet is not to be rejected, the inspection mechanism rotates it through the second 180.degree. increment and releases the pallet onto another pallet car assembly. This pallet car assembly transfers the pallet from the inspection bay to the outfeed bay. A pusher plate is swung downwardly to a position behind the pallet and is actuated to push the pallet against a stop, thereby positioning the pallet for alignment in a stack of pallets on the outfeed elevator.
In the outfeed bay, there are gripper arms for holding the pallet while the pallet car assembly leaves the outfeed bay and returns to the inspection bay. The gripper arms then release the pallet onto the outfeed bay elevator. As pallets are deposited on the outfeed bay elevator, the elevator is indexed downwardly. When the elevator has a full stack of pallets, it transfers the pallets to a conveyor assembly for removal of the stack.
For alignment of a stack of pallets without inspection of the pallets, the apparatus can be operated in the foregoing manner except rotation of the inspection mechanism is deactivated.